README.TXT

Using Polygon Offsets for Efficient Object Translation 
 
 
The PGONOFFS sample demonstrates the use of the polygon-offset call available 
in OpenGL 1.1. Using this call, the depth values of the fragments generated by 
the rasterization of the polygon may be shifted away or towards the origin, 
as an affine function of the window coordinate depth slope of the polygon. 
 
In this sample, a quadric (cylinder, sphere or disk) is drawn normally and 
with a polygon-offset value. A trackball is used to view the object from 
various angles, by dragging it with a mouse. Additionally, the following 
key inputs are recognized: 
 
 Key        Description 
 ---        ----------- 
 left/right Decrease/increase the units in the glPolygonOffset() call. 
 up/down    Increase/decrease the factors in the glPolygonOffset() call. 
 a/A        Decrease/increase the number of stacks in the quadric. 
 c          Toggle on/off culling. 
 f          Cycle through the various quadrics. 
 g/G        Decrease/increase the radius of the quadric. 
 h/H        Decrease/increase the height of the quadric. 
 i          Set initial values for units and factors. 
 t          Toggle on/off texturing. 
 z/Z        Translate the object in Z. 
 1/2/3      Enable GL_POLYGON_OFFSET_FILL/GL_POLYGON_OFFSET_LINE/ 
            GL_POLYGON_OFFSET_POINT. 
 0          Toggle on/off smooth shading. 
 
 
Note 
---- 
 
PGONOFFS will not run on an implementation of OpenGL version 1.0. The OpenGL 
for Windows 95 redistributables included on the Win32 SDK are an 
implementation of OpenGL version 1.0.